The term Cor Pulmonale was introduced by Stuart Harris (1952), Chronic Pulmonary Heart Disease (CPHD) or chronic cor pulmonale; is characterised by hypertrophy of the right ventricle, due to hypertension in the pulmonary circuit caused by chronic lung disease or pulmonary vascular pathology. But CPHD does not include cardiac damage due to pulmonary hypertension of mitral stenosis or congenital heart disease.
The expert committee of the W.H.O. (1961) defined C.P.H.D. as “hypertrophy of right ventricle resulting from disease affecting the function and/or the structure of the lungs, except where these pulmonary alterations are the result of the diseases that primarily affect the left side of the heart or congenital heart diseases”.
Causes of Pulmonary Heart Diseases:
(A) Diseases primarily affecting air passages of the lungs and the alveoli:
1. Chronic bronchitis with generalised airway obstruction with or without emphysema
2. Bronchial asthma or chronic asthmatic bronchitis
3. Emphysema with or without bronchitis or asthma
4. Pulmonary fibrosis with or without emphysema due to:
(a) Tuberculosis
(b) Pneumoconiosis
(c) Bronchiectasis
(d) Other pulmonary infections
(e) Radiation therapy
(f) Mucoviscidosis etc.
(B) Pulmonary granulomata or infiltration:
1. Sarcoidosis
2. Chronic diffuse
3. Berylliosis
4. Eosinophilic granulomata or histiocytosis.
5. Malignant infiltration
6. Dermatomyositis interstitial fibrosis
7. Alveolar microlithiasis
(C) Pulmonary resection may also be a significant factor when a major portion of lung is removed.
(D) Congenital cystic diseases of lungs: a rare cause.
(E) Diseases primarily affecting the movement of the thoracic cage:
(1) Kyphoscoliosis and other thoracic deformities
(2) Thoracoplasty
(3) Pleural fibrosis
(4) Chronic neuromuscular weakness e.g. poliomyelitis
(5) Obesity causing alveolar hypoven tilation (Pickwickian syndrome)
(6) Idiopathic alveolar hypoventilation.
Recurrent subacute pulmonary thrombo-embolism or occlusive diseases of small pulmonary arteries may also lead to cor pulmonale but are rare.
Clinical Features of Pulmonary Heart Diseases:
Clinical features will depend on the background pathology and its effect on the heart though it can be acute, subacute or chronic. Chronic cor-pulmonale is most commonly due to chronic obstructive pulmonary disease, with emphysema. The ultimate effect is raised pulmonary artery pressure causing R.V.H. and high output failure.
Typical patient gives history of chronic cough over many years, due to some form of chronic obstructive airway diseases, (C.O. A.D.) e.g. chronic bronchitis, bronchial asthma and emphysema, the three major causes.
The patient is usually middle-aged, with history of recurrent winter bronchitis or bronchial asthma. He may be a heavy cigarette or ‘Biri’ smoker.
Careful history-taking in some patients may show past history of bronchiectasis, chronic pulmonary tuberculosis, pneumonectomy, thoracoplasty, spinal deformity, occupational lung diseases e.g. silicosis or asbestosis etc. (vide supra).
Regardless of the type of onset, symptoms are almost similar in most patients. As the severity of pulmonary disease increases, gradual development of cardiac decompensation begins, finally leading to right heart failure.
There is history of recurrent cough and wheezing which gradually becomes continuous with gradually increasing dyspnoea. In advanced cases the subject is dyspnoeic at rest; chest expansion is poor; breath sounds are sometimes distant and rhonchi are present all over with scattered crepitations in both lungs. At this stage right heart failure usually occurs; J. V.P. is raised. Liver is enlarged and tender; cyanosis and peripheral oedema are late signs.
Physical signs will depend on the background diseases causing pulmonary hypertension, R.V.H. and finally right heart failure.
Due to emphysema, apex beat is impalpable. Right ventricular thrust is therefore is not easily palpable although it may be present over the epigastrium.
A systolic bruit due to tricuspid incompetence and right ventricular third heart sound may be heard on auscultation. Respiratory infection always makes the situation worse and may end in fatality, if not properly treated. Papilloedema may sometimes be present. In advanced cases, the patient may be drowsy or comatose.
Laboratory Findings on Pulmonary Heart Diseases:
Polycythaemia may be present in established cases. In developing countries evidence of malnutrition often complicates the picture. The author has seen many cases of cor pulmonale associated with hepatic cirrhosis. In factory labourers “biri” smoking and cheap country made alcohol often are in the background. In addition there may be environmental pollution. Hence attention to hepatic function should be given, because malnutrition, alcoholic hepatocelluar injury and congestive failure are all agents in damaging the liver.
Radiography of chest may be normal in early stages but may show emphysematous changes with prominent bronchovascular markings, or features of primary pulmonary diseases. Heart shadow may show right ventricular hypertrophy; pulmonary artery enlargement may be seen in advanced cases. Low diaphragm and tubular heart is usually present.
ECG:
In early cases ECG may be normal. Evidence of right ventricular hypertrophy, right axis deviation, right bundle branch block, accompanied by S pattern across left chest leads may be present. P-pulmonale in ECG is a very typical finding.
Lung function tests will show diminished forced vital capacity from predicted normal, forced expiratory volume (FEV1) is usually less than 75%, expiration is prolonged than normal. In restrictive lung disease there is hardly any obstruction and FEV1 and EVC may be more than 75%. Blood gas analysis may show diminished PO2 and increased PCO2 of arterial blood depending upon degree of respiratory failure.
Diagnosis of Pulmonary Heart Diseases:
Disease is difficult to diagnose in early stage. Long history of respiratory disease, increasing exertional dyspnoea, appearance of mild oedema legs, with radiological and electrocardiographic evidence of right heart strain or enlargement, may help in early diagnosis. Blood gas analysis and lung function tests give supportive evidence. Finally fully developed picture of right sided heart failure sets in. The most important point is to consider the possibility of pulmonary origin of heart failure.
Prognosis of Pulmonary Heart Diseases:
Once congestive heart failure develops the prognosis is poor. Some patients may die within a year or two inspite of treatment. However emergency treatment of respiratory infection as well a heart failure must be done. Oxygen therapy and supportive treatment may prolong the life and comfort to a great extent. In elderly age group there may be associated I.H.D. and hypertensive heart disease to make the situation worse.
Treatment of Pulmonary Heart Diseases:
By the time pulmonary hypertension and cardiac failure sets in, no curative treatment for the underlying lung disease is possible. But most patients are benefited by proper control of pulmonary infection and intensive therapy of congestive heart failure.
Prevention of further Pulmonary Damage:
Smokers should stop smoking for good. The patients should be prevented from exposure to hazardous dusts, fumes, or industrial pollutions. Change of occupation, though difficult, may be necessary. Economic problems often become the limiting factor. Environment and diet are very important.
Control of Respiratory Infection:
This is the most important part of treatment Respiratory infection leads to myocardial hypoxia and usually precipitates heart failure. Proper antibiotics should always be given according to bacterial flora of the sputum. Hyposensitization against common respiratory allergens may sometimes help to prevent recurrent respiratory allergy.
Bronchodilators:
Treatment with bronchodilators always necessary in patients with respiratory distress, as discussed in the chapters on bronchial asthma and chronic bronchitis.
Diuretics:
Reduction of fluid overload improves peripheral circulation reduces C.V.P. and improves oedema. Right ventricular muscle function also improves due to decrease in intravascular volume.
Frusemide or ethacrynic acid are the two diuretics which should be used Judicious use of diuretics prolongs left provide hypokalaemia is avoided and infection is combated with proper use of antibiotics. Oxygen therapy off and on several times a day also improves cardiac function by relieving hypoxia. Oxygen toxicity occurs due to pure or high oxygen concentration for too long a period.
To avoid hypokalaemia, potassium supplements or potassium-sparing diuretics e.g. spironolactone should be prescribed. Acetazolamide is not recommended.
Corticosteroids:
Are also used in cases associated with bronchial asthma. However, inhalational use of beclomethasone is preferable to systemic therapy. But when patients become refractory, bronchodilators and betamethasone inhalation also fails. Prednisolone should be used orally in doses of 20 to 30 mg per day in four divided doses and minimum dosage should be used. It may be possible to tail off the drug within two weeks or may be switched over to inhalation therapy. Parenteral steroids are used only as emergency.
Oxygen Therapy:
Is of great help and often life-saving. Regulated oxygen therapy should be given under close supervision. Best method is to hospitalise the patient but where it is not possible oxygen should be administered at home with usual precautions (risk of fire should be explained). The oxygenation should be adjusted to P02 level above 60 mmHg. At right the flow rate of oxygen may have to be increased to prevent sleep-induced hypoxaemia and possible cardiac arrhythmias. While using nasal catheter, flow-rate of oxygen of 2 to 5 litres per minute ensures oxygen supply of 30 to 40% in inspired air.
In patient of COPD, respiratory centre (R.C.) may become tolerant to rising PCO2 and the action of R.C. is principally influenced by the hypoxaemic stimulus, via carotid sinus and aortic bodies. Sudden removal of this hypoxaemic drive by rapid oxygenation may cause drowsiness, convulsion, coma or even death (carbon dioxide narcosis).
Hence careful oxygenation under close observation is necessary. However, where mechanical ventilatory support is available, this is not a problem.
Inhalation of oxygen above 60% and above, if continued over 36 hours may be damaging to respiratory epithelium and pulmonary surfuctant. This is also likely to occur during prolonged assisted ventilation with high percentage of oxygen.
Most dangerous complication is ventilatory failure (hypoxaernia and hypercapnic respiratory failure) which should be treated preferably in a respiratory care unit.
Mucolytic Therapy:
Thick tenacious sputum alone may cause severe dyspnoea cause small air way blockage. Bronchiolar drainage by suction-aspiration of mucus may even be life-saving. Soft plastic catheters can be used but modern sophisticated instruments are also available (Askrad Lab. Cranford N.J. USA). Even fiberoptic bronchoscope can be used.
It should be realised that even simple suction by soft plastic catheter using local anaesthesia can be life-saving.
Potassium-iodide mixtures and adequate hydration are helpful. Mucolytic agents e.g. bromhexine is commonly used. Bromhexine can be administered orally, parenterally and by inhalation. This is synthetic benzylamine compound obtained from an alskaloid vasicine from a plant Adhatoda vascia.
Oral dose — 8 to 16 mg three times daily.
Acetyl Cysteine:
Acetyl cysteine (Airbron; Mucomist) is also used in USA. It is a derivative of an aminoacid 1-cysteine. It is given by inhalation or through intratracheal catheter or via bronchoscope. Rubber or metal tubes should not be used.
Pancreatic Dornase:
Pancreatic dornase obtained from beef pancreas has been also used. These last two agents may also cause allergic reactions as well side effects.
Right Ventricular Failure:
The picture resembles Congestive cardiac failure (CCF).
In cor pulmonale right ventricle ultimately fails and it should be treated with adequate rest, low salt diet, diuretics, and digitalis and regulated oxygen therapy. Too much salt restriction may result in hypochloraemia. Water intake needs restriction in some cases. Effect of digitalis is not so good as in heart failure due to non-pulmonary cause, but myocardial function shows some improvement. (Refer to the chapter on Heart failure). However, it is provable that digitalis produces its good effects when there is associated left ventricular dysfunction. Occurrence of arrhythmias is likely due to existing hypokalaemia result of prolonged diuretic therapy.
Vasodilators:
Vasodilators are being recently tried which may help, by decreasing right ventricular after- load. Though we are not yet certain about their efficacy in improving right ventricular function, drugs like isosorbide-dinitrate, nifedipine and hydralazine may be tried with caution.
Phlebotomy:
Phlebotomy is an old procedure which may be helpful occasionally in preventing thromboembolic phenomenon and reducing viscosity of blood.
Exercise-conditioning, relaxation-training, use of home ventilators, occupational therapy and vocational rehabilitation may be rewarding. Yoga-therapy also helps to some extent. It increases relaxation and self-confidence due to controlled breathing. But these are of no use once right heart failure is established.
Finally it should be remembered that background disease also determines this prognosis and planning of treatment. Hence all effort should be made to investigate the nature of underlying pathological status.